1. Field of the Invention
This invention relates to reformulated gasolines. In another aspect, this invention relates to methods of gasoline reformulation to produce clean-burning reformulated gasolines.
2. Description of the Related Art
The Clean Air Act Amendments of 1990 require the sale, in the near future, of gasolines which reduce emissions of toxins and ozone-forming volatile organic compounds in certain non-attainment areas. In addition, various states are mandating cleaner burning fuels. In California, for example, the California Air Resources Board has issued regulations mandating that Phase II gasolines sold, in the near future, in their jurisdiction have specified performance characteristics to reduce emissions of the existing vehicle fleet.
These regulatory requirements, along with the public's and industry's desire for improved air quality, create the need for less polluting and more cost-effective vehicle and fuel technologies. Additionally, in the future, other regulatory requirements may be imposed.
For instance, the State of California has become very concerned about not only the mass of vehicle emissions but the tendency of these emissions to form ozone. This tendency of hydrocarbons to form ozone is referred to as "reactivity". Thus, future reformulated gasolines used as clean alternative fuels in low emission vehicles may be required to enable additional reductions of reactivity in vehicle exhaust emissions than is now required.
Thus, there is a need for reformulated gasolines which reduce, relative to existing industry average gasolines, vehicle exhaust emissions levels of both hydrocarbon mass and reactivity and, if possible, simultaneously reduce emissions of toxic compounds ("toxics"), carbon monoxide and nitrogen oxides.
Heretofore, refiners have blended refinery gasoline component streams to meet octane, vapor pressure and temperature range requirements, and there is a great deal of prior art on such blending. Opposite thereto, very little is known on blending to meet emissions requirements.
For instance, one key technical unknown or problem is how to reformulate gasolines with oxygenates without increasing emissions of nitrogen oxides. Some researchers have shown that adding fuel oxygenates to gasoline may increase emissions of oxides of nitrogen. For example, such is discussed in the report of the Auto/Oil Air Quality Improvement Research Program, entitled Technical Bulletin No. 6, "Emissions Results of Oxygenated Gasolines and Changes in RVP", September, 1991, and the Staff Report, "California Phase 2 Reformulated Gasoline Specifications, Volume 2, Proposed Regulation for California Wintertime Oxygenates Program", prepared by the California Air Resources Board, Stationary Source Division, Release Date: Oct. 4, 1991.